经常拆装钢紧固件区域腐蚀防护改进

目的提升经常拆装的钢紧固件区域的腐蚀防护水平。方法通过盐雾试验考察经常拆装对钢紧固件区域腐蚀的影响。制定改进方案,并通过加速腐蚀试验进行验证。结果经常拆装对紧固件区域防护层会产生明显破坏作用,通过更换紧固件表面处理方式、孔壁防护、装配密封和喷涂缓蚀剂等措施可明显提升腐蚀防护水平。结论采用腐蚀防护改进方案可有效解决经常拆装的钢紧固件区域的腐蚀问题,可在飞机制造和使用维护中推广应用。     

直升机结构钢涂层体系防护性能在模拟海洋大气环境中的变化

目的对比、评价服役于海洋大气环境中直升机结构钢防护体系的防护性能。方法通过模拟海洋大气环境加速试验方法,研究直升机结构钢防护体系在实际服役过程中出现的损伤。结果涂层A微观结构较为疏松,加速试验中涂层基体产生鼓泡,并发生腐蚀。电化学阻抗谱(EIS)方法测得低频区的阻抗模值相对较低,说明涂层防护性能较差,与宏观试验结果一致。结论在模拟海洋大气环境的加速试验中,涂层表面的微小缺陷(如疏松结构中的微小孔洞)会成为腐蚀溶液进入的快速通道,进而降低涂层的防护性能。利用电化学阻抗谱(EIS)方法可有效表征有机涂层涂覆下的金属腐蚀行为,并评估涂层的防护性能。     

新型防腐涂层对直升机典型结构材料防护性能研究

目的研究新型防腐涂层对直升机典型结构用铝合金及复合材料在热带海洋性气候环境下的防护性能,并与原防护涂层进行对比。方法通过测试涂层腐蚀后的形貌、光泽度、色差、电化学阻抗等,对比新/原涂层对直升机典型结构用铝合金和复合材料的防护性能。结果经过2年腐蚀后,新涂层表面无明显变化,而原涂层表面有轻微腐蚀,光泽度和色差下降较大。电化学阻抗测试表明,暴露前后涂层结构无明显变化,涂层阻抗值呈现持续下降的趋势,但是原涂层阻抗下降更快。结论新涂层对直升机典型铝合金和复合材料有更好的防护性,更加适于海洋性环境的使用。     

直升机蒙皮典型结构有机涂层防护性能在模拟高原大气环境中的变化

目的评价服役于高原大气环境中的直升机蒙皮典型结构及其防护体系的防护性能。方法通过模拟高原大气环境加速试验方法再现直升机蒙皮典型结构防护体系实际服役过程中出现的损伤,利用扫描电镜对表面微观形貌进行观察,采用电化学阻抗谱测试研究有机涂层阻抗的变化。结果在实验室加速试验中,蒙皮试验件螺钉周边先出现局部腐蚀,之后腐蚀产物又逐渐减少,而铆钉周边经过多个周期后腐蚀产物都没有显著增多。螺钉中间区域有机涂层电化学阻抗模值直至第8个周期后与原始情况相比才大幅度下降,而铆钉中间区域有机涂层电化学阻抗模值在试验中多次明显下降。结论铆钉周边的有机涂层经过多个周期加速试验仍具有阻挡腐蚀性介质的作用。与螺钉结构的情况相比,铆钉中间区域有机涂层防护性能退化显著。     

飞机铝合金结构连接部位表面防护体系修理技术研究

目的研究飞机铝合金结构连接部位表面防护体系修理技术。方法根据飞机铝合金连接结构腐蚀损伤特点、原防护体系类型及服役环境特点等,选取修复材料和修复工艺,制定5种不同的表面防护体系修理方法,通过在飞机典型涂层加速试验环境谱下开展加速腐蚀试验,优选出适于飞机铝合金结构连接部位表面涂层损伤修理方法。结果加速试验2周期,采用RM4修理的试件,修复部位表面开始出现脱落现象。加速试验6周期,在紧固件区域,采用RM1,RM2,RM3,RM5修理的试件在变色、粉化、开裂、起泡和剥落指标上都属于优或者良,但在生锈指标上仅采用RM3修理的试件属于良;在非紧固件区域,采用RM1,RM2,RM3,RM5修理的试件在各指标上都属于优或者良。结论 RM3更适用于飞机铝合金结构连接部位表面防护体系修理。     

某型飞机腐蚀关键结构含涂层模拟件腐蚀行为研究

目的研究某型飞机腐蚀关键结构防护涂层体系的腐蚀失效行为,评估涂层的防护性能,为整机日历寿命体系评定和飞机大修提供试验依据。方法在编制加速环境谱的基础上,对模拟件进行环境谱作用下的加速腐蚀试验。结果在经过修理前后两个阶段的加速腐蚀后,模拟件在铆钉连接区域表面涂层均出现不同程度的鼓包、开裂、剥落等老化现象。结论腐蚀关键结构表面防护涂层体系总体上能够满足首翻期和翻修间隔期内结构的表面防腐要求,但在外场使用维护中应针对铆钉、螺钉连接件周围等腐蚀敏感部位加强防护,一旦出现涂层老化、破损等损伤需要及时进行局部修复。在科学、合理的外场使用维护条件下,可以适当延长飞机的进厂大修时间。     

多因素综合海洋气候自然加速试验技术相关性和加速性验证

目的对新研发的多因素综合海洋气候环境自然加速试验技术相对热带海洋气候环境户外暴露试验的相关性和加速性进行验证。方法分别采用多因素综合海洋气候环境自然加速试验装置和对应的试验方法企业标准,以及传统的户外暴露试验方法,以不同表面处理工艺的汽车紧固件、标准金属、有机涂层和塑料为样品进行验证试验,采用Spearman秩相关系数法和加速因子(AF)法对相关性和加速性进行进一步验证。结果紧固件、标准金属和有机涂层在多因素综合海洋气候环境自然加速试验和海洋气候环境户外暴露试验过程中,都表现出相同的腐蚀失效模式。多因素综合海洋气候环境自然加速试验相对远海场(离海岸线350 m)户外暴露试验紧固件秩相关系数为1,镀锌镍合金紧固件、无铬锌铝涂层紧固件、拉弗莱紧固件和石墨烯紧固件的加速倍率分别为7.7,11.3,10.3,13.5倍;标准金属秩相关系数为0.8,Q235、工业纯铝、工业纯锌和工业纯铜的加速倍率分别为11.8,11.5,9.3,3.7倍。多因素综合海洋气候环境自然加速试验相对海洋平台户外暴露试验标准金属秩相关系数为1,Q235、工业纯铝、工业纯锌和工业纯铜的加速倍率分别为3.4,2.1,4.5,2.2倍。结论多因素综合海洋气候环境自然加速试验相对海洋气候环境户外暴露试验具有良好的相关性,而且对海洋平台的相关性更好。对于紧固件表面处理工艺、标准金属和有机涂层而言,多因素综合海洋气候环境自然加速试验相对海洋气候环境户外暴露试验具有高的加速倍率。     

2024铝合金连接结构两种防护涂层耐蚀性研究

目的研究铝合金两种防护涂层在5%NaCl盐雾环境下的腐蚀疲劳性能。方法针对在两种涂层防护作用下的2024铝合金连接结构,开展实验室加速试验,采用"腐蚀环境-疲劳加载"交替循环的试验模式,得到铝合金两种防护涂层在5%NaCl盐雾环境下的腐蚀疲劳寿命值,对比分析涂层体系对铝合金连接结构的腐蚀疲劳寿命影响。结果 5%NaCl盐雾环境对于铝合金连接结构疲劳寿命有较大影响,相较于传统涂层,纳米涂层在5%NaCl盐雾环境下的防护效果更好。结论纳米涂层表面破坏后快速生成的致密氧化膜能有效提高涂层的耐蚀性能。     

高强度合金结构钢与高强度铝合金防护层的耐霉性研究

目的研究高强合金结构钢和高强铝合金防护层的耐霉菌腐蚀能力。方法以高强合金结构钢和高强铝合金两种材料为基材分别制备不同防护层,按GJB 150.10A—2009进行实验室霉菌试验,评定防护层的长霉等级。结果两种材料的不同防护层中,除润滑油涂层和阳级氧化层的长霉等级为0~1级外,炮油涂层、涂漆层、镀锌层或锌镍合金层长霉等级均在2~3级。结论高强合金结构钢润滑油涂层耐霉性能良好,镀锌层或锌镍合金层、涂漆层、炮油涂层耐霉性能较差;高强铝合金阳级氧化层耐霉性能良好,炮油涂层、涂漆层耐霉性能较差。     

直升机旋翼桨叶有机涂层防护性能在户内加速试验中的变化

目的考核评价高原环境下服役的直升机旋翼桨叶典型结构及其防护体系的耐腐蚀性能。方法利用建立的模拟高原环境加速试验谱,再现直升机旋翼桨叶结构防护体系实际服役过程中出现的腐蚀损伤,采取电化学阻抗谱测试研究涂层阻抗的变化。结果经历8个周期的户内加速试验后,新修桨叶试验件表面有机涂层Bode曲线呈现小幅下降,即有机涂层防护性能下降;报废桨叶试验件表面有机涂层的特定频率电化学阻抗模值与原始情况相比仅下降了不到1个数量级。结论报废桨叶试验件表面有机涂层电化学阻抗模值曲线在8个周期后仍然小幅高于未经历户内加速试验的新修桨叶试验件。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.